1. Field of the Invention
The present invention relates to moisture-curable compositions containing polyisocyanates having (cyclo)aliphatically-bound isocyanate groups and compounds containing alkoxysilane groups, which can be rapidly cured in the presence of moisture to form coatings, adhesives and sealants.
2. Description of the Prior Art
It is known that polyisocyanate resins are curable in the presence of atmospheric moisture to form polyurea coatings. During the curing mechanism an isocyanate group reacts with moisture to form an amino group, which then reacts with another isocyanate group to form a urea group. One of the disadvantages of these moisture-curable resins is that the curing mechanism is relatively slow.
Accordingly, it is an object of the present invention to provide moisture-curable resins having an increased curing rate.
This object may be achieved with the compositions of the present invention, which contain moisture-curable polyisocyanates in admixture with compounds containing alkoxysilane silane groups. The faster curing rates obtained from the compositions of the present invention are surprising because the compounds containing alkoxysilane groups, which are also curable in the presence of moisture, cure more slowly than polyisocyanates. However, when mixtures of these two types of compounds are present, a faster curing rate is obtained.
Copending applications, U.S. Ser. Nos. 09/172,751 and 172,584, describe polyisocyanates that have been modified to contain both isocyanate groups and alkoxysilane groups. The modified polyisocyanates cure faster than the unmodified polyisocyanates and compounds containing alkoxysilane groups. The copending applications are not directed to mixtures of polyisocyanates and compounds containing alkoxysilane groups.